1. Field of the Invention
The present invention relates to an engine ignition control apparatus for an internal combustion engine. More particularly, the present invention relates to an engine ignition control method and apparatus which correct an advance angle of ignition timing based on a rate of change of an engine rotary speed.
2. Description of the Background Art
There is a known engine ignition control apparatus which detects an acceleration state of a vehicle, and which adjusts ignition timing in response to the detected acceleration state. An example of an ignition timing control method of this type is disclosed in published Japanese Patent Document JP-B-7-51925.
The ignition timing control method, as disclosed in published Japanese Patent Document JP-B-7-51925, detects an acceleration command operation performed by a rider, based on a change in throttle opening, and applies a retarding angle correction to ignition timing when an engine rotary speed is decreased in such a state, thereby preventing knocking.
However, according to the method of ignition timing control as disclosed in Japanese Patent Document JP-B-7-51925, an acceleration state of the vehicle is detected based on a change in a throttle opening. Accordingly, for example, during the acceleration when a throttle opening is held in a fully open state, it may be difficult to detect whether the vehicle is in an acceleration state based on a change of the throttle opening.
Hence, there exists a drawback in the method of ignition timing control of the Japanese Patent Document JP-B-7-51925, since it is impossible to perform a control for determining ignition timing using a change in a throttle opening, as one of control parameters.
The present invention has been made to overcome such drawbacks of the existing ignition timing control method and apparatus. Accordingly, it is one of the objects of the present invention to provide an engine ignition control apparatus which overcomes the above-mentioned drawback of the related art, and which detects an acceleration state of a vehicle based on a rate of change of an engine rotary speed and appropriately corrects an ignition timing advance angle.